This invention relates to overload responsive circuit breakers which are mounted in a panelboard or load center for protecting apparatus connected in a branch distribution circuit. More particularly, this invention relates to circuit breakers of the aforementioned type wherein the electrical connection of the circuit breaker to the power supply of the panelboard or load center is effected by bolt-in connection of a terminal of the circuit breaker to a supply bus of the panelboard or load center. Specifically, the invention is related to an improved retaining structure for loosely captivating a rotatable element of cooperable threaded fastener means on the terminal of the circuit breaker while the circuit breaker is detached from the panelboard or load center.
It is desirable to captively retain the rotatable threaded fastener element of a bolt-in circuit breaker in operative position on the terminal of the breaker to prevent loss during shipping and handling and for convenience and safety during installation. Electrical connection of circuit breaker terminals to panelboard or load center supply bus are customarily located at the rear of the breaker, substantially remote from the front surface thereof, and access to the fastener element is therefore restricted. By retaining the fastener element in operative position on the circuit breaker terminal, an installer can readily attach the circuit breaker to the panelboard or load center and complete the electrical connection thereof with a screwdriver or similar tool. The installer is not required to reach into a hard to access location to position a loose fastener while attempting to engage that fastener with a tool, potentially dropping the fastener to fall to an undetermined location within the panelboard apparatus whereat it could significantly reduce opposite polarity electrical spacings of that apparatus if not retrieved before power is applied to the panelboard.
An example of bolt-in circuit breakers mounted within a panelboard is shown in U.S. Pat. No. 4,358,815 issued Nov. 9, 1982 to H. E. Koslosky et al and assigned to the assignee of this application. In that patent, a cylindrically shaped threaded nut is retained in position on the terminal of a circuit breaker by a nylon retainer having a loop surrounding the body of the nut and a tongue tucked under an insulating sleeve which is shrink-fit over a leg of the circuit breaker terminal. Although the retainer described therein is well suited for its intended purpose, the assembly method is expensive and is not well suited for automated circuit breaker assembly.
Other retainers have been attempted for use in an automated assembly circuit breaker, but for one reason or another were found to be less than well suited for the intended purpose. For example, in one embodiment a wire loop was placed around the body of the fastener, and the ends of the wire loop were brought closely together, then formed to extend parallel, substantially radially from the loop through an opening in the terminal. The distal ends of the wires were formed over to engage the rear side of the terminal to prevent withdrawal through the opening. However, this structure did not positively locate the fastener in the proper orientation on the terminal for testing purposes during assembly and did not adequately position the fastener in an operative position for installation. Another version provided a cage on the terminal member loosely captivating the threaded fastener therein by forming four outwardly projecting lateral legs in successive right angles to overlie the threaded fastener at four distinct corners, but this version significantly increased the complexity, cost and width of the terminal assembly.
Another example of retention of a bolt-in terminal fastening means element is shown in copending U.S. application Ser. No. 07/192,997 filed May 12, 1988, in the names of Dean A. Hubbard et al entitled "Bolt-In Circuit Breaker With Improved Terminal Fastener Retainer" and assigned to the assignee of this invention, now U.S. Pat. No. 4,825,338, issued Apr. 25, 1989. In that application a flexible plastic member having a loop surrounding a cylindrically shaped threaded nut has a tongue which snaps into a slot in the terminal strap to retain the nut on the terminal strap. The plastic member has integral fingers formed parallel to and outboard of the tongue, the fingers being deflected by the terminal strap to bias the nut against a surface of the terminal strap. This version allows the nut to float angularly during breaker installation, out of axial alignment with the threaded post, requiring the installer to align the cooperating fastener elements during connection of the nut and post.